Printing mechanism



June 13, 1939. L FROYD 2,162,427

PRINTING MECHANISM Filed April 20, 1956 2 Sheets-Sheet l L. W. FROYDPRINTING MECHANISM June 13, 1939.

Filed April 20, 1936 2 Sheets-Sheet 2 Patented June 13, 1939 PATENTOFFICE PRINTING MECHANISM Lawrence Wilbur Froyd, Arlington, Va.,assignor to Albert Falk Doig, Washington, D.

Application April 20, 1936,- Serial No. 75,456

Claims.

This invention relates to improvements in printing mechanisms of themultigraphing type, and more particularly to a method and apparatus forinking such mechanisms while in operation.

5 In printing with duplicating machines of the multigraphing type, it iscustomary to impart impressions. of characters or type carried by aprinting cylinder of the machine to the surface to be printed through atransfer ink ribbon mounted over the characters or type on the cylinder.As each duplicate is produced, the transfer ink ribbon is advanced overthe character or type surface with a step-by-step movement. It willtherefore be apparent that, as impressions are produced, the ink contentof the ribbon will be rapidly depleted, necessitating frequent removalof the ribbon to replenish its ink content. It will be apparent furtherthat, as the transfer ribbon advances over the type surface, the inkcontent of the ribbon will gradually decrease to a minimum toward therear end of the ribbon. As a result thereof, the printed impressionsobtained will be of varying intensity and the printing of theintroductory area of the impression will be darker than that of theclosing area, thereby destroying the similarity of the printed letter toan actual typewritten letter.

Attempts have been made to overcome these defects by inking the ribbonwhile in operation.

All such attempts have heretofore proved unsuccessful. Workers in thisart have employed stationary ribbons and have applied ink directly tothe ribbon surface. This method appears to be objectionable in that theribbonwear is concentrated in a localized area, resulting in blurredprinting and a material decrease of the life of the ribbon. Othermethods have contemplated the application of a surplus of ink directlyto the inking ribbon and subsequently removing the surplus by passingthe ribbon under a wiper. These methods have likewise provedunsuccessful in that the wiper rapidly becomes saturated with ink,resulting in a gathering of ink between the lines, of type causinginterlinear streaks on the printed surface. The use of wipers is furtherobjectionable in that repeated contacts of the ribbon and wiper tend towear the ribbon material resulting in blurred printing and decreasedribbon life.

All previous attempts in this art to supply ink directly to the movingribbon of the multigraphing type of printing mechanism while the machineis in operation, have been unsuccessful. Such failures may be attributedto the fact that heretofore operators have permitted the transfer ribbonto advance when it is under the pressure of the inking rollers. Thisnecessarily results in stretching the ribbon each time an impression isobtained. As a result, the ribbon is caused to lose shape and wear outrapidly. Such '5 methods further resulted in an uneven applica tion ofink.

The present invention contemplates an improvement for overcoming theabove objections and comprises a cam attachment as a substitute 10 forthe present eccentric employed in the standard multigraphing machine,which cam alters the sequence of operation of the present machine andpermits re-inking of the ribbon while the machine is in operation,insuring a uniform disl5 tribution of ink throughout the ribbon for eachindividual printing with a minimum amount of ribbon wear.

It is accordingly an object of this invention to provide a method andapparatus for re-inking 20 the movable transfer ribbon of a printingmechanism while the machine is in operation in a manner to elfect auniform distribution of ink in the ribbon.

It is further an object of this invention to 25 provide a method andapparatus for reinking the movable transfer ribbon. of a printingmechanism while the machine is in operation whereby to obtainimpressions of uniform intensity,

It is further an object of this invention to provide a cam mechanism forcontrolling the advance of the transfer ribbon of a duplicating machineand effecting movement of the transfer ribbon when the same is out ofcontact with the inking attachment and the platen. 35

These and other objects will readily become apparent from thespecification which follows when considered with the accompanyingdrawings which show the preferred form of my invention. gm

Reference is made to the accompanying draw? ings, of which- Figure 1 isan end elevation of a duplicating machine of the multigraphing type;

Fig. 2 is a partial vertical section on line 2-2 45 of Fig. 1, showing aribbon feeding mechanism;

Fig. 3 is an end elevation of the inner face of a feeding. cam andsupporting plate therefor shown in section in Fig. 2;

Figs. 4 to 6 are diagrammatic views illustrat- 5O ing the sequence ofoperation embodied in my invention; and

Fig. 7 shows a portion of a ribbon feeding mechanism.

The printing mechanism disclosed in Fig. l is 55 of conventionalstructure and includes the usual printing cylinder I, cylinder supports2, side plates 3, transfer ink ribbon 4 and platen 5. The cylinder maybe rotated in a counter-clockwise direction, as seen in Fig. 1, by meansof the crank 6 or other suitable driving means. Ink may be applied tothe transfer ribbon by an ink fountain attachment 1 of the usual type.The particular inker disclosed is the seven roller type and comprises anink fountain 8, transfer roll 9 and intermediate rolls l0 and Ink isapplied to the transfer ribbon 4 by the transfer roll 9.

According to my invention, the ink is applied to the transfer ribbonwhile the ribbon is stationary with respect to the printing cylinder. Itis impossible to obtain this result when the standard eccentric andeccentric strap, or any-modification thereof, is employed, in view ofthe fact that the eccentric and eccentric strap advance the transferribbon continuously through 180 degrees of the rotation of the printingcylinder. To accomplish the desired result, I employ a cam attachment inplace of the usual eccentric to control the ribbon feeding mechanism. Apreferred form of cam is shown in detail in Figs. 2 and 3 and comprisesa plate 12 provided with a recessed track or cam slot Hi. The plate I2is secured to the side plate 3 and the cam slot is adapted to receive aroller follower l4. As shown in Fig. 2, the roller I4 is secured on thefree end of apin I5, which, in turn, is secured firmly to a radiallymovable main operating bar It. The bar i6 is constructed and operatessimilarly to the radial bar shown in Fig. 5 of Patent 1,807,322. The barI6 is forked at its lower end to straddle the shaft '11 to be guidedthereby. The upper end of the bar It carries a perforated lug l8slidably mounted on a radial pin l9 carried by the drum spider 20.

According to the prior art, as shown by Patent 1,807,322, an eccentricstrap such as 8| in that patent is utilized to cause the operating pinto move in and out radially. Obviously, the movement of an eccentricstrap about an eccentric is exactly similar on either side of its centerline, and such an eccentric control can only move such a bar 85 radiallyoutwardly uniformly during one-half rotation of the eccentric andradially inwardly uniformly during the following half rotation of theeccentric. When such an eccentric is used, it is necessary to rotate thedrum degrees to move the eccentric strap its full throw inwardly, duringwhich complete period, the ribbon is uniformly advanced one step.

Fig. '7 shows the details of the ribbon feeding mechanism according tothe prior art. The control bar Hi atits lower end is formed in a fork 2!which straddles the shaft ll. A pair of dogs 22 are pivotally carried onbar IS in position to engage a pair of ribbon drums. These drums arerotated by the dogs 22. As shown, when the left hand dog is moveddownwardly by pin I5 and bar l6, it will engage teeth'23 secured to oneend of the ribbon drum to rotate the latter to feed the ribbon 4.

The pitch surface of the cam slot is designed so that the total fallrequired to advance the transfer ribbon the required amount occurswithin an arc of approximately 83 degrees, so situated on the cam platel2 that such advance of the transfer ribbon takes place when the ribbonis entirely out of contact with the inking "rolls and the platen. Theremaining 277 degrees of the 'most point of the cam slot.

are encompassed by the cam slot is adapted to cause the necessary riseof the roller follower to place the ribbon advancing mechanism in properengagement with the ribbon take-up and feed spools, preparatory toadvancing the same.

Figs. 4 to 6 represent, in diagrammatic form, three successive relativepositions of the cam slot, inking roller, printing type and rollerfollower. In these figures, the type surface 2| of the cylinder has beenrepresented as rotating in a clockwise direction. In Fig. 4, a printingoper ation is indicated as commencing, the leading edge of the typesurface having just engaged the platen roller 5. The roller follower I4,at this instant is positioned in and at the lower- In Fig. 5, the typesurface and adjacent transfer ribbon have moved a short distance underthe inking roller 9 and the impression is almost completed. The roller Mhas moved through the same are as has the surface 2 I, but the cam slothas caused the roller to move a short distance away from the axis of thedrum. Continued rotation of the drum will position the parts as shown inFig. 6 wherein the inking operation has just been completed. At thisinstant, the roller M has reached the highest point in the cam slot andthe roller is now positioned at its maximum distance from the drumcenter.

In operation, the cylinder is rotated by the handle 6 and paper is fedbetween the cylinder I and platen 5. The position of the roller followerat the instant the printing operation begins is indicated schematicallyin Fig. 4. As the cylinder I continues to rotate, the roller followeradvances in the cam slot causing the bar [6 to move gradually away fromthe drum center. Continuing the rotation of the printing cylinder, thetype surface and transfer ribbon start to pass under the inking rolleras indicated at Fig. 5. Further rotation of the cylinder completesprinting and continues the inking of the transfer ribbon. When, byrotation of the cylinder, the transfer ribbon covering the type surfacehas passed beneath the inking roller, the roller follower will havereached the highest point or peak of the rise of the cam slot asindicated at Fig. 6. At this instant, the type surface and transferribbon have passed out of contact with the inking roller. der throughonly about 83 degrees causes the roller follower to move to its originalinnermost position indicated in Fig. 4, thereby advancing the ribbon onestep to present a uniformly inked ribbon area to the type surface.

It will be apparent from the foregoing that the transfer ribbon will bereinked while the printing machine is in operation in such a manner asto effect a uniform distribution of ink on the ribbon for eachimpression, thereby obtaining copies of constant intensity withoutadditional ribbon wear.

What I claim is:

1. In a multigraphing machine, a drum, means to rotate the drum, saiddrum having a printing form on the face thereof, a platen with which theprinting form may coact, an inking ribbon in contact with the printingform, an inking roller positioned to engage said ribbon after it haspassed from under said platen, a stationary drum support, cooperatingmeans on said drum and support for sliding said ribbon over the face ofsaid printing form, and being operable in timed relation to slide theribbon onlyafter the printing form has been moved under said roller to aposi- Further rotation of the cylinv,

tion in advance of said roller, said means comprising an endless cammember and a member in engagement therewith, one of said members beingmovable with respect to the other upon movement of the drum.

2. In a multigraphing machine,'a drum means to rotate the drum, saiddrum having a printing form on the face thereof, a platen with which theprinting form may coact, an inking ribbon in contact with the printingform, an inking roller positioned to engage said ribbon after it haspassed under said platen, a support for the drum, said drum beingmovable with respect to the sup,- port, said plate being provided withan endless cam surface, an operating bar slidably mounted for radialmovement on said drum, a pin extending from said bar and beingpositioned to engage said surface, means operably responsive to movementof said bar radially inwardly to slide said ribbon over the face of saidprinting form, said cam surface being formed and positioned to move saidpin and bar only after the printing form has been moved from under theinking roller and before the printing form has been moved to engage saidplaten.

3. In a multigraphing machine, a drum, an inking ribbon associated withsaid drum, means to rotate the drum, a support for the drum, said drumbeing movable with respect to the support, said support being providedwith an endless cam surface, an operating bar slidably mounted forradial movement on said drum, a pin extending from said bar and beingpositioned to engage said surface, means operably responsive to movementof said bar and pin for feeding said ribbon over the drum.

4. A ribbon feed control for a multigraphing machine comprising a plate,said plate being provided with an endless cam surface, a drum, a ribbonassociated with the drum, means to rotate said drum, a pin supported bysaid drum in position to engage said surface and being movable by saidsurface during rotation of the drum, and means responsive to movement ofsaid pin for feeding the ribbon over the drum.

5. In a multigraphing machine comprising a rotary drum provided with aprinting form and a ribbon in contact therewith, a platen associatedwith said drum, said drum and formlbeing rotatable through a portion ofone revolution to cooperate with said platen and complete an impression,means to apply ink to said ribbon throughout another portion of therevolution, a stationary drum support, cooperating means on said drumand support for feeding said ribbon over the drum after application ofthe ink and prior to engagement of the drum and printing form with theplaten, said means comprising an endless cam member and a pin member inengagement therewith, one of said members being mounted on the drumsupport, the other member being mounted on the drum, and means operablyresponsive to movement of the last-named member for feeding said ribbonover the drum.

LAWRENCE W'ILBUR FROYD.

